Amorphous carbon-coated ZnO porous nanosheets: Facile fabrication and application in lithium- and sodium-ion batteries

Abstract

Rational design and facile synthesis of ZnO-based electrode materials for highly reversible and high-rate lithium storage still remain a significant challenge. Herein, carbon-coated ZnO (abbreviated as C-ZnO) 2 dimensional (2D) porous nanosheets are successfully achieved by a scalable hydrothermal method followed by a chemical vapor deposition process. The ultrathin ZnO nanosheets possessing net-like structures are uniformly coated by a layer of amorphous carbon ∼5 nm in thickness. The amorphous carbon coating can not only effectively improve the electrical conductivity and durability of the ZnO nanosheets but also act as a buffer to accommodate the large volume strain during cycling. Furthermore, the porous C-ZnO nanosheets afford both large electrode/electrolyte contact interfaces and short Li+/Na+ diffusion paths. As anode materials of lithium- and sodium-ion batteries (LIBs and SIBs), the C-ZnO structured composites exhibit excellent electrochemical performances. The C-ZnO electrodes exhibit high reversible capacities of 851 mAh g−1 after 50 cycles at 100 mA g−1 and 804 mAh g−1 after 200 cycles at 1000 mA g−1 for LIBs. Significantly, the prepared C-ZnO can be a promising anode material for lithium ion battery.